It is claimed that the MEG, alone or in combination with the EEG, is much better than the EEG alone for localizing some sources in the brain. Although this is true in simplified theory, there has been no actual experimental test of this claim. The purpose of this work is to perform a definitive test, and see if this claim is indeed true. This test is definitive because it will be performed in the live human head, with a completely known source. The source here will be a current dipole due to an electrical catheter already implanted in the head of patients for seizure monitoring; a tiny current will be passed between the contacts on the catheter to produce the source dipole. First, before the measurement in actual patients, the entire source system and measuring system will be tested in a mock-up saline head. Then, in the patient, MEG and EEG spatial maps over the head will be measured due to the implanted dipole. Next, an inverse solution will be performed on these maps to locate the source. The solution will be performed on MEG maps alone, on MEG plus EEG maps, and on EEG maps alone. Finally, a comparison will then be made between locations determined by these three types of maps to see how well the MEG (alone or in combination with the EEG) duplicates the true source location in comparison to EEG alone. The test will be done for a total of dipoles in each of three patients, in order to verify this comparison for a number of locations in the head, and for different head geometries. Human use approval has already been obtained, complete with special restrictions and conditions for the safety and welfare of the patient. Because of the growing interest and effort in the MEG by many groups, this test should have important consequences in guiding the future of the MEG.